Antenna



30, 199. R. w. MASTERS ANTENNA Filed Jan. 27, 1945 NVENTO.

Patented Aug. 30, 1949 fio'rporation' dffimerica, a' 'corporatifin of Dela- Aisiflicatim January '27, 19%, Ser'i'al N0.- straits -11 Gla'irfis; (01. 250-8353) fii in ipa f -The ririipal' db jet of'the instant invention ist'o ovfde ani prove type ofantenna, in i i h'ic diatof elm'iitsconsist of flatsheets ravin inc er'object isto proyideantennas of the described typewhieh resiinple and rugged in structure While providing efiicient operation rremwaytraaa band of frequencies. fafthr -olojectis' -toproyideantennas of the f -Stl a ther bb'jectjof-the'presentinvention is (1e nnas'of the describedtype suitifatid'n and-*ieeenan of horizontally 'pofl'ariaedradi'oWaves. V where and other objects wilbbecoine apparent to those skilled in the art upon consideration of arerenewing aescripnoi; withreference to the fa ompafiyingl'raWingEbfwhich:

igiire l' isa perspective View of" one layer of 'ristile type antenna mbodying the instant nticn, V I igure" z isaperspective view of amultilayer anterii'i'aof the type illiistra'ted in Figure 1;Wherem the radiators of theyarioiis layers 'are' merged 7 form eontinuin'is sheets, and Figure 3 i's aneleyationof a dipole type antenfia -e1nbot lying the invention. Y

Referring' first to Figure lgfo'ur fiat plates 01' sheets l 3,-"5 ahd '1 are "disposed radially at 90 "intervals around a*tlibular eoridilctive mast 9. one edg'eof each sheet lies' paralleland closely -adjacent"t'o the inast 1. Thi's edge isineach caseconnected'at its top and bottom to the mast eat the points I l andl3:-Each sheet is approximately one-half wavelength long, at the mean frequency "at-which the antenna is to operate, and; extends approximately one-quarter wavelength in width radial-ly outward from the mast 9.

Fourwires or lines l5, l1, l9 and 2| extend upwarary Within the inast' 9 as snowngzir tlriey may lie outside "the mast; Thel ins I5, 'I'I,' l9 aindZl are connectedtd the sheets-I, 3, 5 and 1 respec- """rnidpoifits "22, 23, 25am 2"! respecel sma'tedrrcm themastits'lfandmay,

if ties edf'be s'urroiinded withindividual groiindear-sheaths "shown in Figure '3 and de- 10 a mere detailWvithTfren'c tothat m;-

' irei'itional tlirnsti-le'strlicture; The lines 15, 1-1, rs

and -25 "may be connected togetherand "to the traiis'ihitte'r' or ceiv'er in any known'wa 'tc provide" the rqilird "cii'r're'ht phase relationships. one suitable connection is shown arid described in ows. Patm- 2;08'6;976, issued July 13; 1937 to G:-H;Brown.

Th'e ciirrnt distribution in the sheet elements ofthe' antennaof Figure 118 511611 as'to provide'a vertical -"d-i1ctiwiity a proximating that 'of a single layer of a turnstile*aritenria of"cohventi0nal design; such thatshown "in the abo'v'e' 'mentiond"l'zilatei'i't. Although the exact manner in which the current fio'ws is "not known atpre'se'nt, it has been found "experimentally that the structiire'bf-Fi'giirefl ha's'a rlativelylcroad resonance characteristic,permitting efficientoperation over a' Wide 1 frequency band. I It is'believed that theoperationissomewhat as -follows-:= Each of the sheets, for example, the s'heet c'ooperates' with 'the opposite sheet and perhaps=alsothemast 9 to'act as a parallel conductor transmission line one-half Wavelength long; shorted at'itsends"ll and 13 and fd atits center 221 -'Ihis*i'e.'sults in a standing wave; with maximum'voltageat the point 22am! zero voltage at the shortedpointslr and I3. Each'horizontal-element ofthe sheet I *constitute's a radiator connected to the 1i-ne,-'with current-flowingin it-in a' direction radial-to the'mast 9. Thefields produced by these elements add together to pro-.

duce a resultant field approximating that which would be provided by a single radiator of conventional form. However, it is probable that the voltage distribution along the parallel line varies with variation of the frequency from the resonant frequency, changing the currents in the elements of the sheet I, with the result that the overall impedance remains relatively constant.

The vertical directivity may be increased as in the conventional turnstile antenna, by providing a series of layers of elements spaced vertically apart from each other along the mast 9. If the vertical spacing between centers of corresponding elements is made one-half wavelength, the sheets of each panel of radiators will merge to form a Single sheet, as shown in Figure 2. In this arrangement, four sheets ll, I03, I and I01 are disposed around the mast I09 at 90 intervals, like the sheets of Figure 1. Each sheet is an integral number of half wavelengths long, and is connected to the mast at half wavelength intervals, beginning at the top, at points I I3.

vEach point I22 midway between two of the points H3 is connected to a feed line, as in the system of Figure 1. The arrangement is such that all of the points H3 in any one sheet are energized in phasewith each other. The arrangement of Figure 2 will provide vertical directlvity approximating that of a conventional turnstile of equivalent dimensions, retaining the broad resonance characteristics of the single layer system of Figure 1.

Referring to Figure 3, the invention is applied to a. dipole type structure, comprising a pair of sheet radiators 2M and 203 supported in a common plane on opposite sides of a mast 209, and connected thereto at their upper and lower ends 2 and H3. Each sheetnnay comprise a screen or network of horizontal wires, supported between vertical conductors 229. The centers of the members 229 closest the mast 209 are connected to coaxial transmission lines having outer sheaths 2i 5 and H9 and inner conductors 2l5' and 2l9. The inner conductors H5 and 2l9' are connected to the sheet radiators 2M and 203 while the outer sheaths 2 l5 and 2| 9 are connected at their upper ends to the supporting mast 209.

The operation of the system of Figure 3 is similar to that of one pair of radiators in the system of Figure 1. The directive characteristics are approximately those of conventional dipole, and the resonance characteristics are relatively broad. If desired, vertical layers of dipoles may be employed to provide increased vertical directivity as in the system of Figure 2.

It will be apparent without further illustration that the sheets in the structures of Figures 1 and 2 may be made in the form of screens, as in the structure of Figure 3, and that continuous sheets may be substituted for the screen radiators in the system of Figure 3. Although it has been stated throughout the above description that the sheet elements are fed at their midpoints, they may be energized at any other point along the edge adjacent the mast if a. lower input impedance is desired. The maximum impedance appears at the midpoint.

The invention has been described as a broad band antenna structure including radiator elements in the form of fiat sheets of conductive material, each disposed with one edge closely adjacent and parallel to a grounded support. The edgeis connected to the support at intervals of Substantially one-half wavelength, and fed at the 4 point or points approximately midway between the connections to the support. This arrangement provides broad band characteristics, with the advantages of a simple and economical structure.

I claim as my invention:

1. An antenna system including a vertical mast of conductive material, a plurality of sheets of conductive material of generally rectangular shape and approximately one-half wavelength long and one-quarter wavelength wide, disposed in planes radially of said mast, each having one of its longer edges adjacent said mast, connections from the upper and lower ends of each of said edges to said mast, and means for applying radio frequency energy to said sheets at points substantially midway of said edges.

2. An antenna system including at least one radiator element comprising a plane sheet of conductive material approximately one-half wavelength long and one-quarter wavelength wide, a grounded conductive member disposed parallel to and adjacent one of the longer edges of said sheet, and connected to said edge at the ends of said sheet, and transmission line means including an outer conductor connected to said grounded member and an inner conductor connected to said sheet at a point on said edge displaced from said ends.

3. An antenna system including at least one radiator element comprising a plane sheet of conductive material of generally rectangular shape, a conductive supporting member disposed parallel to and adjacent one of the edges of said sheet, and connected to said edge at the ends of said sheet, and transmission line means including an outer conductor connected to said supporting member and an inner conductor connected to said sheet at substantially the midpoint of said edge.

4. An antenna system including a plurality of radiator elements, each comprising a plane sheet of conductive material approximately one-half wavelength long and one-quarter wavelength wide, a conductive supporting member disposed parallel to and adjacent one of the longer edges of said sheet, and connected to said edge at the ends of said sheet, and transmission line means including an outer conductor connected to said supporting member and an inner conductor connected to said sheet at substantially the midpoint of said edge.

5. An antenna system comprising a generally tubular conductive supporting member, at least one fiat sheet of conductive material supported by and disposed radially of said supporting memher, said sheet including one substantially linear .edge disposed adjacent and parallel to said supporting member and connected thereto and grounded for radio frequency potential at the ends of said edge, a transmission line conductor extending within said support and insulated therefrom and connected to said sheet at a point on its said edge displaced from said ends.

6. An antenna system of the turnstile type, in-

cluding at least one layer of four radiator ele- -ments, each of said elements comprising a elements, each of said elements comprising a vertically disposed flat sheet of generally rectangular shape, grounded at the ends of one of its vertical edges and fed at the center of said vertical edge.

8. An antenna system comprising, as a radiating or receiving element a substantially plane sheet of conductive material and of a generally rectangular shape, said sheet having one lengthwise substantially straight edge and being grounded for radio frequency potential at the ends of said edge, a width substantially equal to a quarter Wave length at the operating frequency, a length substantially equal to an integral number of half wave lengths at the operating frequency and points of voltage nodes substantially integral half Wave lengths apart on said edge, said points including said grounded ends, a support for said sheet, and a transducer connected to said sheet.

9. An antenna system comprising, as a radiating or receiving element a substantially plane sheet of conductive material and of a generally rectangular shape, said sheet having one lengthwise substantially straight edge and being grounded for radio frequency potential at the ends of said edge, a width substantially equal to a quarter wave length at the operating frequency, a length substantially equal to a half wave length at the operating frequency, a support for said sheet, and a transducer connected to said sheet.

10. An antenna system comprising a plurality of radiating or receiving elements, each of said elements including a substantially plane conductive sheet of generally rectangular shape a quarter wavelength wide by an integral number of half wavelengths long at the operating frequency and disposed in a radial plane about a common axis and being substantially co-extensive axially with each of the other of said sheets, each of said sheets having one substantially linear lengthwise edge adjacent to and substantially parallel to said axis and closely spaced from the other said adjacent lengthwise edges, each of said sheets being grounded for radio frequency potential at the ends of said adjacent lenghwise edges, the radio frequency voltages at the operating frequency at those points on the said linear edges of any two sheets which points lie in the same plane normal to said axis being substantially equal in amplitude, a support for said elements, and a transducer connected to said sheets.

11. An antenna system comprising, as radiating or receiving elements, a pair of substantially plane sheets of conductive material each of a generally rectangular shape, each of said sheets having one lengthwise substantially straight edge and being grounded for radio frequency potential at the ends of said edge, a width substantially equal to a quarter wavelength at the operating frequency, a length substantially equal to an integral number of half wavelengths at the operating frequency and points of voltage nodes substantially integral half wavelengths apart on said edge, said points including said grounded ends, said sheets being disposed with said lengthwise edges closely adjacent and parallel to each other and in a common plane, a support for said sheets, and a transducer connected to said sheets.

ROBERT W. MASTERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,658,761 Crance Feb. 7, 1928 1,960,006 Hagen May 22, 1934 2,298,449 Bailey Oct. 13, 1942 FOREIGN PATENTS Number Country Date 119,851 Switzerland July 19, 1926 OTHER REFERENCES Advertisement in Electronics, March 1946, pages 12 and 13. 

